General aviation aircraft engines are subject to a variety of high stress conditions that may compromise the electrical conductivity of the cables and their connectors at both the spark plug and magnetos ends. These engines produce very high temperatures and may be used in both very hot and very cold environments. High altitude application and high humidity conditions also threaten connector and cable integrity. Because of these challenging conditions, igniter cable connectors must be watertight and must not be affected by changing temperature, pressure and humidity conditions. For these reasons, various types of high voltage ignition cable connectors and igniter leads have been developed for use in aircraft engines.
U.S. Pat. No. 6,668,810 issued to St. John et al. is directed to an ignition coil assembly with spark plug connector to provide more reliable electrical connection between the high voltage terminal of the ignition coil and the spark plug terminal. This invention provides for a spark plug boot formed of a highly resilient material with an internal coil type high voltage connection spring in the boot section that electrically contacts the coil and the spark plug terminals. The internal passageway of the coil boot features a uniform cylindrical diameter with a number of ribs that are provided to engage the center section of the coil type spring specifically the center section of said spring that has a radius greater than the end segments thereof. A connection spring has a center section with an outside diameter that is slightly less than the inside diameter of the boot passageway. The boot passageway has a plurality of radially inwardly protruding ribs that engage with the center portion of the spring thus ensuring that the boot is held in place and thus the spring maintains an effective connection with the high voltage terminal of the spark plug.
U.S. Pat. No. 5,957,706 issued to Phillips, Jr. et al. is directed to an ignition cable terminal assembly that includes a coil spring that engages the upper annular shoulder of a ring gear that biases the ring downwardly against a lower gear. Ultimately this produces a tight motion-free engagement of the terminal assembly with the stud terminal which is plugged into the spark plug.
U.S. Pat. No. 5,827,079, issued to Murata is directed to an electric connection member, ignition apparatus for internal combustion engine and manufacturing method thereof. The conductor is composed of a coil spring with a contact member that connects the coil to the spark plug. This invention includes a coil spring with a large diameter portion which is smaller than the inside diameter of a cylinder portion of a first rubber cap and the inside diameter of the adapter. The contact member from the coil then connects through the spring to a high-tension terminal of the spark plug. A groove portion of the inside wall of the adapter prevents the rotation of the contact member.
U.S. Pat. No. 5,630,722 issued to Mochizuki et al. describes an ignition cable connection fitting to which a high voltage current is supplied. The connection is made by means of a contact spring connecting to a contact member by means of a terminal of a spark plug. A coil spring acts on the ignition cable connection which in turn is held in position about the spark plug by means of a locking device that engages the connection fitting with the spark plug so that the connection is not easily disconnected.
U.S. Pat. No. 2,398,359 issued to Curtiss discloses a shielded elbow shell spark plug connector. The spark plug connector has one end connected to an aviation spark plug and the other end connected to an electrical conductor. The connector has a hollow metal elbow or shell that is formed of two complementary pressed sheet metal shell halves brazed together and having a union brazed to end and a retainer is brazed to the spark plug connection arm. The completed metal elbow shell is placed in a die with an electrical conductor or cable connector insert held in spaced relation for a molding operation of plastic insulating material that is forced inside.
While other variations exist, the above-described designs for high voltage ignition cable connectors and igniter leads are typical of those encountered in the prior art. It is an objective of the present invention to provide a securely fastenable general aviation engine igniter lead assembly. It is a further objective to provide an igniter cable assembly that provides complete sealing against moisture and dirt found in the aviation environment. It is yet a further objective to provide an igniter assembly that may be easily disassembled and reassembled for maintenance purposes without damage to the assembly or the igniter components. It is an additional objective of the invention that the connection to the magneto end of the igniter cable be removable from the magneto housing without removing the entire housing. It is a final further objective of the invention to provide the above-described capabilities in an inexpensive and durable connector that is capable of extended duty cycles. While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.